Technical Field
The present invention relates to a headphone unit and an ear muff unit.
Background Art
A typical headphone set includes a pair of housings each accommodating a driver unit. The housings are joined to each other with a head band. These housings are each provided with an ear pad attached thereto. The housings are joined to respective supports which are joined to the two respective ends of the head band.
The positions of the housings relative to the head band and the relative posture between the housings should be adjustable depending on the physical size or preference of the user. To satisfy the requirements, the housings may be fixed to the respective supports of the head band with screws in a possible fixing structure. Unfortunately, the movable ranges of the housings relative to the supports depend on the tightening torque of the screws or dimensions of the housings and supports. Such tightening torque of the screws and dimensions of the components are difficult to control in mass production. In addition, the housings cannot move smoothly relative to the supports, because the housings and supports are composed of hard materials such as plastics.
In such circumstances, a requirement for a headphone set including housings with ear pads is smooth movement of the housings relative to the supports.
A conventional headphone set with a microphone is disclosed in Japanese examined utility model application publication No. H06-44232, for example. The headphone set includes, for example, an annular wave spring and two annular resin plates holding the spring therebetween on the mounting surfaces of a microphone holder and a headphone hanger.
Another headphone set is disclosed in Japanese examined utility model application publication No. H07-18228, for example. The headphone set includes a holder having a groove along its axis. After insertion of a microphone boom through the groove, the holder is inserted into the body of the headphone set. The microphone boom is held by spring force of the holder.
A device for mounting driver units is disclosed in Japanese examined patent application publication No. H08-32099, for example. The device includes a cabinet and a substantially spherical rotation shaft integrated with the cabinet and held between receiving portions on the inner surfaces of a pair of holders. The holders are rotatably mounted to the cabinet.